<template>
    <div class="left-slider">
        <div class="content"
        @touchstart='touchStart'
        @touchmove='touchMove'
        @touchend='touchEnd'
        :style="deleteSlider"
        @click="$router.push(`/chat?uid=${linkItem['uid']}&name=${linkItem['name']}&union_id=${linkItem['union_id']}`)">
        <!-- 插槽中放具体项目中需要内容 -->
        <slot></slot>
        </div>
        <div class="remove active" ref='remove' @click="handleClick">删除</div>
    </div>
</template>
 
<script>
  export default {
    props:{
      item:Object,
      propE: {
        type: Object,
        default: function () {
        }
      }
    },
    data() {
      return {
        startX:0,  //触摸位置
        endX:0,   //结束位置
        moveX: 0,  //滑动时的位置
        disX: 0,  //移动距离
        deleteSlider: '',//滑动时的效果,使用v-bind:style="deleteSlider"
      }
    },
    computed:{
        linkItem(){
            if(!this.item.list[this.item.list.length - 1]['isLeft']){
              return this.item.list[this.item.list.length - 1]['extra']
            }else{
              return this.item.list[this.item.list.length - 1]['user']
            }
            
        }
    },
    methods:{
      handleClick () {
        this.$emit('removeItem')
        this.deleteSlider = "transform:translateX(0px)";
      },
      touchStart(ev){
        ev= ev || event;
        //tounches类数组，等于1时表示此时有只有一只手指在触摸屏幕
        if(ev.touches.length == 1){
          // 记录开始位置
          this.startX = ev.touches[0].clientX;
        }
      },
      touchMove(ev){
        ev = ev || event;
        //获取删除按钮的宽度，此宽度为滑块左滑的最大距离
        let wd=this.$refs.remove.offsetWidth;
        if(ev.touches.length == 1) {
          // 滑动时距离浏览器左侧实时距离
          this.moveX = ev.touches[0].clientX;
          //起始位置减去 实时的滑动的距离，得到手指实时偏移距离
          this.disX = this.startX - this.moveX;
          // 如果是向右滑动或者不滑动，不改变滑块的位置
          if(this.disX < 0 || this.disX == 0) {
            this.deleteSlider = "transform:translateX(0px)";
          // 大于0，表示左滑了，此时滑块开始滑动
          }else if (this.disX > 0) {
            //具体滑动距离我取的是 手指偏移距离*5。
            this.deleteSlider = "transform:translateX(-" + this.disX*5 + "px)";
            // 最大也只能等于删除按钮宽度
            if (this.disX*5 >=wd) {
              this.deleteSlider = "transform:translateX(-" +wd+ "px)";
            }
          }
        }
      },
      touchEnd(ev){
        ev = ev || event;
        let wd=this.$refs.remove.offsetWidth;
        if (ev.changedTouches.length == 1) {
          let endX = ev.changedTouches[0].clientX;
          this.disX = this.startX - endX;
          //如果距离小于删除按钮一半,强行回到起点
          if ((this.disX*5) < (wd/2)) {
            this.deleteSlider = "transform:translateX(0px)";
          }else{
            //大于一半 滑动到最大值
            this.deleteSlider = "transform:translateX(-"+wd+ "px)";
          }
        }
      }
    }
  }
</script>
 
<style lang="stylus">
.left-slider{
    width: 100%;
    height:70px
    position: relative;
    user-select: none;
    .content{
        position: absolute;
        left: 0;
        right: 0;
        top: 0;
        bottom: 0;
        background:#fff;
        z-index: 100;
        transition: 0.3s;
        display flex
        align-items center
    }
    .remove{
        position: absolute;
        width:100px;
        height:70px;
        background:red;
        right: 0;
        top: 0;
        color:#fff;
        text-align: center;
        font-size: 14px;
        line-height: 70px;
    }
}
</style>